The goal of the proposed research is to develop a highly sensitive and specific radioimmunoassay for leukotriene E4 and leukotriene E4-N-acetate, two important metabolites of leukotriene C4 and D4. These leukotrienes are potent bronco and coronary artery vasoconstrictors, increase vascular permeability, stimulate mucus secretion, and cause long lasting hypotension, and thus play a pathophysiological role in immediate hypersensitivity reactions, inflammation, and tissue trauma. Specific aims include: 1) preparation of a number of leukotriene E4 and leukotriene E4-N-Ac-protein conjugates having various modes of leukotriene to protein linkage, 2) production of antibodies to each conjugate by immunization of rabbits, 3) comparison of the antibodies and selection of those with highest specificity and sensitivity, 4) production of leukotriene E4 and E4-N-Ac radioimmunoassay kits for commercialization. A large number of pharmaceutical companies are developing novel and more specific therapeutic agents based on leukotriene inhibition and/or antagonism and these kits are expected to find wide application. The investigations into the effects of the conjugate structure on antibody sensitivity and specificity are novel and are expected to lead to technological innovation.